1. Field of the Invention
The present invention relates to a time sharing frequency synthesizer having general application in several types of communications systems.
2. Description of the Prior Art
U.S. Pat. No. 4,479,248, issued to Caspari et al, discloses a frequency synthesizer tuning system having a microprocessor. The system comprises a variable oscillator and microprocessor coupled thereto for the control thereof, the microprocessor having a programmable counter therein which is used for measuring the output frequency of the variable oscillator. However, no time sharing concept is disclosed in this system.
U.S. Pat. No. 4,479,226, issued to Prabhu et al, discloses a frequency-hopping single side band mobile radio system. The transmitter for this system functions to modulate the input signal by "hopping" it to a different carrier frequency every few seconds while the receiver to the system employs the identical carrier sequence as used by the transmitter to demodulate the transmitter carrier-frequency-hopped SSB signal thereby recovering the original single side band signal.
U.S. Pat. Nos. 2,510,338, issued to Guanella, and 2,530,824, issued to King, both disclose frequency synthesizers using multiple frequency sources. Neither of these systems discloses microprocessor control of the frequency synthesizer. U.S. Pat. Nos. 4,394,776 and 4,403,342, both issued to Borras et al, and U.S. Pat. No. 4,317,221, issued to Toya, all disclose frequency synthesizers and both a transmitter and receiver. They do not, however, disclose any time sharing concept. U.S. Pat. Nos. 4,190,807, issued to Weber, 4,194,151, issued to Gregersen et al, 4,153,884, issued to Ikeguchi et al and 4,081,752 issued to Sumi, all disclose frequency synthesizer systems. However, there is no disclosure of using these systems in a time sharing mode.
U.S. Pat. No. 3,204,034, issued to Ballard et al discloses a multiplexed frequency synthesizer. Neither microprocessor control nor a time sharing concept are disclosed in this reference.